Individuals with Multi‐Joint Osteoarthritis Demonstrate Larger Longitudinal Declines in Frailty: Data from the Canadian Longitudinal Study on Aging

OBJECTIVE: Test the hypothesis that multi-joint osteoarthritis would modify the relation between time and frailty progression, where more affected joints would lead to larger declines over 6-years compared to those without osteoarthritis using data from the Canadian Longitudinal Study on Aging. METHODS: Frailty was quantified using a frailty index at baseline, 3-year, and 6-year follow-up. Osteoarthritis was self-reported physician diagnosis of knee, hip, or hand. Participants were categorized as having none, one, two, or three affected joints at baseline. Linear mixed-effects models adjusted for age, body mass index, marital status, sitting time, light-moderate physical activity, strenuous physical activity, and sex were performed to test the interaction between time and multi-joint osteoarthritis on frailty trajectories over 6-years. RESULTS: 13,757 participants were included (mean frailty: 0.16±0.05); 10,193 had no osteoarthritis, 2,535 had one affected joint, 806 had two, and 223 had three. Individuals without osteoarthritis had the lowest baseline frailty, followed stepwise by one-joint group, two-joint group, and three-joint group (p<0.001). Baseline multi-joint osteoarthritis was positively associated with frailty progression over 6-years [β=0.105, 95%CI: 0.027:0.170]. Frailty slopes across groups were; no osteoarthritis [β=0.237, 95%CI: 0.225:0.247], one-joint group [β=0.293, 95%CI: 0.262:0.310], two-joint group [β=0.348, 95%CI: 0.327:0.368], and three-joint group [β=0.330, 95%CI: 0.291:0.371]. Frailty progressed faster in multi-joint (≥2 joint group) versus single-joint osteoarthritis [β=0.070, 95%CI: 0.029:0.109]. CONCLUSION: Individuals with osteoarthritis affecting two-or-three joints experienced a 40-47% faster rate of frailty progression compared with those without osteoarthritis despite starting at a higher baseline frailty, highlighting multi-joint involvement as a marker of heightened risk of accumulating health deficits.